DIVALENT EUROPIUM IN SILICA-GELS

Eu2+ has electronic transitions between the 4f(7) ground state and the 4f(6)d(1) first excited state. These transitions are very sensitive t o the surroundings in which the ion is embedded. Due to this character istic, divalent europium has been employed as a sensitive optical prob e. For this work we prepared silica gels doped with Eu2+ ions. The dop ing was achieved in two different ways, as explained in the text. Exci tation and emission spectra were taken, and from the excitation data a very small splitting between the T-2g and E-g levels was calculated. This splitting implies that the impurity ions are located in a weak cr ystalline electric field as can be expected for this kind of amorphous materials. (C) 1998 Elsevier Science S.A.